Principle Of Detailed Balance Research Articles

A note on the Cotton flow and the Ricci flow for three-manifolds, and the Hořava–Lifshitz gravity

We consider the more general geometrical flow in the space of metrics for three-manifolds that consists of a combination of two flows, the Cotton flow and the Ricci flow; by playing a fundamental role in the detailed balance principle of the four dimensional Hořava–Lifshitz gravity, this generalized flow reveals another difficulty with this theory that attempts to be a candidate for an UV completion of Einstein general relativity, namely, the supposed emergency of the speed of light, the Newton constant, and the cosmological constant, from a deeply nonrelativistic theory of gravity. Respecting that principle, the generalized flow shows the proliferation of different limits of the theory with an unwanted behavior at both the IR and UV regimes.

Julian Hirniak, an early proponent of periodic chemical reactions

In this article we present and discuss the work and scientific legacy of Julian Hirniak, the Ukrainian chemist and physicist who published two articles in 1908 and 1911 about periodic chemical reactions. Over the last 110+ years, his theoretical work has often been cited favorably in connection with Alfred Lotka’s theoretical model of an oscillating reaction system. Other authors have pointed out thermodynamic problems in Hirniak’s reaction scheme. Based on English translations of his 1908 Ukrainian and 1911 German articles, we show that Hirniak’s claim (that a cycle of inter-conversions of three chemical isomers in a closed reaction vessel can show damped periodic behavior) violates the Principle of Detailed Balance (i.e., the Second Law of Thermodynamics), and that Hirniak was aware of this Principle. We also discuss his results in relation to Lotka’s first model of damped oscillations in an open system of chemical reactions involving an auto-catalytic reaction operating far from equilibrium. Taking hints from both Hirniak and Lotka, we show that the mundane case of a kinase enzyme catalyzing the phosphorylation of a sugar can satisfy Hirniak’s conditions for damped oscillations to its steady state flux (i.e., the Michaelis–Menten rate law), but that the oscillations are so highly damped as to be unobservable. Finally, we examine historical and factual misunderstandings related to Julian Hirniak and his publications.

Optical multiscale model for quantification of photon recycling including incoherent light scattering

A comprehensive multiscale modeling framework for photon recycling in textured solar cells and LEDs is introduced, treating light absorption and emission on an equal footing under consideration of the full internal mode spectrum in the device. The framework seamlessly merges a coherent emission model, free from unphysical divergence and ensuring consistency with detailed balance principles, with an incoherent net-radiation model applied to optically thick layers. The scattering of light at nonplanar interfaces is taken into consideration through four characteristic mappings that depict the microscopic scattering process, which are calculated analytically or by using a Monte-Carlo ray-tracing method. The final output of the model consists of energy- and angle-resolved local emission, re-absorption, and energy flux rates for further coupling to electronic transport. To validate the model, it has been compared with analytical solutions for the re-absorption probability in an ideal semiconductor slab with either ideal Lambertian or flat surfaces. The comparison between analytical and numerical calculations shows excellent agreement.

Evaluating Photovoltaic Conversion Performance under Artificial Indoor Lighting

Several photovoltaic technologies, based on different semiconductor absorbers with band-gap energy in the range Eg = 1.0–1.5 eV are currently sharing the market for outdoor applications. These photovoltaic cells are designed to achieve an optimal photovoltaic conversion under solar illumination (represented by the standard AM1.5 global spectrum), but their performance changes under different artificial indoor lights. Here, the detailed balance principle that was first applied for an ideal photovoltaic absorber under solar radiation is now used by considering the actual spectra of four typical indoor lamps: incandescent, halogen, metal halide and white LED. For each particular illumination source, the theoretical maximum for short-circuit current, open-circuit voltage and maximum power point have been calculated and represented as a function of the absorber band-gap energy. Furthermore, the optical absorption spectra of some semiconductors with optimal solar conversion efficiencies are used to estimate their comparative performance under the various artificial light sources. It has been found that wide band-gap absorbers (Eg~1.9 eV) are needed to achieve a light-to-electricity conversion efficiency of 60% under LED illumination or 31% with metal halide bulbs, while a lowest band-gap energy of about 0.8 eV is required to obtain a maximum efficiency of 24% with incandescent and halogen lamps.

Study of 113In(α, α) elastic scattering to determine α-optical potential relevant for astrophysical γ-process

Abstract The α-optical potential is one of the key input parameters used to measure the reaction rate of the (γ, α)-process using the Hauser-Feshbach statistical model and the principle of detailed balance. α-elastic scattering experiment on 113In p-nucleus was carried out in the energy range E lab = 26−32 MeV. The vacuum evaporation technique was used to prepare the 113In target (∼86 μg cm−2). An energy-dependent local optical potential parameters set was obtained by analysing the experimental elastic scattering angular distribution data. The local potential parameters are extrapolated for lower energies and are used to calculate the 113In(α, γ) reaction cross-section.

Use of rational approximations for phonon density of states in evaluation of neutron thermal scattering law

We propose and explore a new analytical formulation for evaluation of Thermal Scattering Law (TSL) using continuous phonon spectra for neutron inelastic scattering. It involves approximating Phonon Density of States (PDOS) in terms of rational approximations in energy transfer. Debye Waller coefficient calculated with these forms are in reasonable agreement with LEAPR calculated values. TSL can be expanded as a power series, each term of which can be integrated analytically. The method leads to TSL being a series of exponential cosine integrals which again have closed rational forms in energy transfer. Their shapes are analogous to asymmetric resonance line shapes and show maxima for certain values of energy transfer which could correspond to phonon emission or absorption. The series is shown to be convergent and easy to compute as it does not involve any numerical integration. The approach is applied to Beryllium metal and Graphite which have vastly different PDOS shapes, and is shown to be capable of giving most of the trends shown by TSL and cross section results from NJOY nuclear code processing system, even with smaller number of power series terms. Since TSL can be calculated for both negative and positive energy transfer with equal ease, one can easily check for the validity of the approximation obeying Principle of Detailed Balance (PDB). The results overall have shown promise of our formulation in making a case for rapid calculations of TSL and also for using the rational forms in energy transfer for analysis of experimental/calculated PDOS data.

Understanding and Weakening Photon Recycling in Solar Cells to Approach the Radiative Limit.

Photon recycling plays an important role in the light outcoupling of state-of-the-art solar cells and is considered a necessary condition to achieve the radiative limit of open-circuit voltage (VOC) and efficiency. However, due to the impact of photon recycling on bulk and surface radiation of solar cells being overlooked, experimental demonstrations on the accuracy of existing photon recycling models are scarce and some contrary theoretical results also emerge. Here, the relationship between photon recycling and radiation processes, as well as the corresponding VOC losses of solar cells based on the principle of detailed balance is clarified. It is shown that weakening photon recycling is more effective to boost the device performance than enhancing it, promoting the theoretical efficiencies of solar cells, such as perovskite, Si, and GaAs, to 98.5%, 94.9%, and almost 100% of their radiative limit, respectively. Moreover, weakening photon recycling also helps to maintain higher efficiency when the internal radiative efficiency decreases, which benefits higher device stability. This work provides an in-depth understanding of the role of photon recycling in solar cells and helps to push efficiency to a new limit.

Importance of Strange Sea to the Charge Radii and Quadrupole Moment of $J^P=\frac{1}{2}^+,\frac{3}{2}^+$ Baryons

Abstract A statistical framework in conjugation with the principle of detailed balance is employed to examine the low-energy properties, i.e. charge radii and quadrupole moment, of JP = $\frac{1}{2}^+$ octet and JP = $\frac{3}{2}^+$ decuplet baryons. The statistical model relies on the assumption that the baryons can be expanded in terms of quark–gluon Fock states. We systematically apply operator formalism along with the statistical approach to study the charge radii and quadrupole moment of baryons. Based on the probabilities of all possible Fock states in spin, flavor, and color space, the importance of sea with quarks and gluons is studied. The individual contribution of the constituent quarks and sea (scalar, vector, and tensor sea) is explored. Due to the large mass difference between strange and nonstrange content, the SU(3) breaking effect is also investigated. The extent to which strange $q\bar{q}$ pairs are considered in sea is constrained by the mass of hadrons and the free energy of gluons, in accordance with experimental evidence. We focus on the individual contribution of strange and nonstrange sea ($g, \langle u\bar{u}\rangle$, $\langle d\bar{d}\rangle$, and $\langle s\bar{s}\rangle$) accommodability in the respective hadrons for their charge radii and quadrupole moment. The present work has been compared with various theoretical approaches and some known experimental observations. The obtained results may give valuable information for upcoming experimental findings.

State-to-state study of non-equilibrium recombination of oxygen and nitrogen molecules.

Rapidly cooled mixtures are of interest for several applications, including hypersonic flows due to the presence of strong cooling temperature gradients in regions such as hypersonic boundary layers and expanding nozzles. There have been very few studies of rapidly cooled mixtures using the high-fidelity rovibrational databases afforded by abinitio potential energy surfaces. This work makes use of existing rovibrational state-specific databases to study rapidly cooled mixtures. In particular, we seek to understand the importance of thermal non-equilibrium in recombining mixtures using both rovibrational and vibrational state-to-state methods for oxygen and nitrogen molecules. We find that although there is significant non-equilibrium during recombination, it is well captured by the vibrational state-specific approach. Finally, we compare the global recombination rate computed based on the state-specific recombination rate coefficients and the global recombination rate computed based on the time local dissociation rate coefficient, which is reversed using the principle of detailed balance. The local dissociation rate coefficient is computed by weighting the state-specific dissociation rate coefficients with the state-specific distribution of energy states. We find a large difference between these rates, highlighting a potential source of errors in hypersonic flow predictions.

Enthalpy of the N+ + H2 → NH+ + H Reaction—Experimental Study of the Reverse Process

The formation of nitrogen hydrides in the interstellar medium is initiated by the nearly thermoneutral reaction of N+ + H2 → NH+ + H. Here, we experimentally determine the enthalpy of this reaction using the principle of detailed balance from a measurement of the rate coefficient of the reverse reaction NH+ + H → N+ + H2. The measurements were carried out in a linear radiofrequency 22-pole trap combined with an effusive beam source of atomic hydrogen at temperatures between 10 and 100 K. The resulting ground-state energy difference (or reaction enthalpy at 0 K) of ΔE 0 = (18 ± 4) meV confirms that there are no significant energy barriers on the reaction path.

Drift–Diffusion Simulation of Intermediate Band Solar Cell: Effect of Intermediate Band Continuity Constraint

Self-consistent drift–diffusion model has been widely employed to simulate the device performance of intermediate band solar cell (IBSC) under practical device configuration. However, one of the remained issues in the drift–diffusion modeled-based works is the difficulty to reach the IB carrier continuity through the self-consistent manner. In most of the previous reports the constraints were relaxed or just partially satisfied; which render the unreliable performance results and misguide the device design strategy. In this work, in order to solve this issue and to validate our results, we performed extensive simulations to fully disclose the significant effect of the IB continuity constraints by taking InAs/GaAs quantum dot-based IBSC as a model device using the semiconductor modules in COMSOL Multiphysics combined with the Fortran codes. We found that under rigorous satisfaction of IB continuity constraint, the band potential profiles for the IBSC with either doped or nondoped IB under various light illumination conditions are nearly identical to those under the dark conditions. Moreover, from the simulated current–voltage curve dependence on the light concentration ratio, we found the device performance based on drift–diffusion under rigorous IB continuity constraint showed similar tendency to the features simulated based on detailed balance principle except the much-lowered power conversion efficiency. Our work demonstrated here, serves as an accurate and reliable IBSC device design approach toward better IB material screening, efficiency improvement, optical management, and extended application in the emerging field such as the perovskite material-based IBSC.

Improved thermonuclear rate of42Ti(p,γ)43V and its astrophysical implication in therpprocess

Context.Accurate42Ti(p,γ)43V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rpprocess) that occurs in X-ray bursts.Aims.We aim to improve the thermonuclear rates of42Ti(p,γ)43V based on more complete resonance information and a more accurate direct component, together with the recently released nuclear masses data. We also explore the impact of the newly obtained rates on therpprocess.Methods.We reevaluated the reaction rate of42Ti(p,γ)43V by the sum of the isolated resonance contribution instead of the Hauser-Feshbach statistical model. We used a Monte Carlo method to derive the associated uncertainties of new rates. The nucleosynthesis simulations were performed via the NuGrid post-processing code ppn.Results.The new rates differ from previous estimations due to the use of a series of updated resonance parameters and a direct S factor. Compared with the previous results from the Hauser-Feshbach statistical model, which assumes compound nucleus43V with a sufficiently high-level density in the energy region of astrophysical interest, large differences exist over the entire temperature region ofrp-process interest, up to two orders of magnitude. We consistently calculated the photodisintegration rate using our new nuclear masses via the detailed balance principle, and found the discrepancies among the different reverse rates are much larger than those for the forward rate, up to ten orders of magnitude at the temperature of 108K. Using a trajectory with a peak temperature of 1.95×109K, we performed therp-process nucleosynthesis simulations to investigate the impact of the new rates. Our calculations show that the adoption of the new forward and reverse rates result in abundance variations for Sc and Ca of 128% and 49%, respectively, compared to the variations for the statistical model rates. On the other hand, the overall abundance pattern is not significantly affected. The results of using new rates also confirm that therp-process path does not bypass the isotope43V.Conclusions.Our study found that the Hauser-Feshbach statistical model is inappropriate to the reaction rate evaluation for42Ti(p,γ)43V. The adoption of the new rates confirms that the reaction path of42Ti(p,γ)43V(p,γ)44Cr(β+)44V is a key branch of therpprocess in X-ray bursts.

Sea contribution to the charge radii and quadrupole moment of JP ½+, ³⁄₂+ baryons

Abstract An operator formalism is used on the wave function of baryons to compute their charge radii and quadrupole moments. The total anti-symmetric wave function in spin, color, and flavor space is framed for $J^P=\frac{1}{2}^+$ nucleons and $J^P=\frac{3}{2}^+$ hyperons. To understand the importance of the sea, a statistical model is used in conjugation with the detailed balance principle. Within the statistical approach, the importance of the sea with quarks and gluons are studied using the relevant probabilities that are associated with spin, flavor, and color space. The present work also focuses on individual contributions of valence and sea which contains terms of the scalar, vector, and tensor seas. The obtained results are in agreement with available theories and a few experimental outcomes. Our computed results may provide important information for upcoming experimental findings.

AXIOMATIC PRINCIPLES AND DETAILED BALANCE

This article presents an analysis of scientific papers and research on axiomatic principles and detailed balance, we are convinced that even today, in accordance with modern requirements, there is still a need to address axiomatic principles and detailed balance, methods and methods for their study. As mentioned earlier, the axiomatics of statistical physics is reduced to the principle of equal probability of the existence of an equilibrium closed physical system in all microstates accessible to it. This postulate, in turn, suggests that the time-averaged probability of the direct and reverse transition of the system between two selected groups of microstates in the accessible region of the phase space must be the same in both directions (this follows from the definition of an equilibrium state, which contains the requirement of stationarity). In fairness, it should be noted that the principle of detailed balance is not a consequence of the axiomatic principles of statistical physics, and therefore, strictly speaking, is not required to be applied within the framework of this axiomatics. There are situations and outcomes we have given in this article, when the principle of equal probability of available microstates in a closed system is satisfied, but the principle of detailed statistical equilibrium is not.

Experimental study of 37Cl(α,n)40K reaction in order to constrain the reaction rate of destruction of 40K in stars

40K is one of the main isotopes responsible for the radiogenic heating of the mantle in Earth-like exoplanets [1] and hence, plays a very important role in the internal geophysical dynamics of a planet. The abundance of 40K in the mantle and the core of such planets is not always possible to be determined by astrophysical observations, although constraining the nuclear reaction rates of 40K during stellar evolution can also lead to constraining the present amount of 40K in these planets, which will improve our understanding on the habitability potential of Earth-like exoplanets. This study aims to constrain the 40K(n,α)37Cl reaction rate, one of the two major destruction paths of 40K in stellar nucleosynthesis,by measuring the reverse reaction 37Cl(α,n)40K and applying the principle of detailed balance as we have done before for the 40K (40K(n,p)40Ar reaction rate) [2]. During the first set of measurements we performed differential cross-section measurements of the 37Cl(α,n1γ)40K, 37Cl(α,n2γ)40K and 37Cl(α,n3γ)40K reaction channels, for six different center of mass energies in the range between 5.1 and 5.4 MeV. The experiment took place at the Edwards Accelerator Laboratory of Ohio University. The gamma rays from the reaction channels mentioned above were detected by two LaBr3 scintillators. Using the swinger facility to change the angle of the beam-target system with respect to the detection system, we were able to take measurements for the differential cross-section at six different angles between 20° and 120° in the lab system.

Optimizing the photovoltaic effect in one-dimensional single-wall carbon nanotube @ MoS2 van der Waals heteronanotubes

One-dimensional single-wall carbon nanotube (1D-SWCNT)@MoS2 van der Waals (vdW) heteronanotubes (HNTs) have inherited extensive attention due to their fascinating properties and increasing mature methods. However, the curvature and chirality dependence of photovoltaic properties in such kind of 1D systems remain unclear. In our work, we explore the electronic and photoelectric properties of 1D-SWCNT@MoS2 vdW HNTs based on the atomic-bond-relaxation approach and the modified detailed balance principle by quantization of band offset and carrier transport behaviors. We find that the optimized power conversion efficiency (PCE) of zigzag-SWCNT@zigzag-MoS2 HNTs is ∼5.3% at the diameter of 3.1 nm, while that of zigzag-SWCNT@armchair-MoS2 HNTs is ∼4.9% at 3.3 nm. Moreover, the PCE can be enhanced further by intercalating h-BN layers at the interface of 1D-vdW HNTs. Our results suggest that 1D-SWCNT@MoS2 HNTs can be served as promising building blocks for the new type of photovoltaic devices.

Optical and acoustic phonon temperature measurements using electron nanoprobe and electron energy loss spectroscopy

Measuring temperature at a high spatial resolution is a fundamental technique for investigating local static and dynamic thermal properties in various materials and devices. Here, we report temperature measurement by electron energy loss spectroscopy using monochromated electron probes of 1--2 nm diameter and large scattering vectors of electrons and based on the principle of detailed balancing between the annihilation and creation of phonons. Temperatures defined by optical and acoustic phonons are evaluated separately. We demonstrate that the use of acoustic phonons is advantageous for low-temperature measurements with higher accuracy. The scheme is applied to evaluating local temperatures in a diamond nanowire during Joule heating. We also discuss the Joule heating mechanism and key factors for improving temperature measurement accuracy.

Resonances in nitrobenzene probed by the electron attachment to neutral and by the photodetachment from anion.

We probe resonances (transient anions) in nitrobenzene with the focus on the electron emission from these. Experimentally, we populate resonances in two ways: either by the impact of free electrons on the neutral molecule or by the photoexcitation of the bound molecular anion. These two excitation means lead to transient anions in different initial geometries. In both cases, the anions decay by electron emission and we record the electron spectra. Several types of emission are recognized, differing by the way in which the resulting molecule is vibrationally excited. In the excitation of specific vibrational modes, distinctly different modes are visible in electron collision and photodetachment experiments. The unspecific vibrational excitation, which leads to the emission of thermal electrons following the internal vibrational redistribution, shows similar features in both experiments. A model for the thermal emission based on a detailed balance principle agrees with the experimental findings very well. Finally, a similar behavior in the two experiments is also observed for a third type of electron emission, the vibrational autodetachment, which yields electrons with constant final energies over a broad range of excitation energies. The entrance channels for the vibrational autodetachment are examined in detail, and they point to a new mechanism involving a reverse valence to non-valence internal conversion.

SECOND-ORDER PHASE TRANSITIONS IN CRYSTALLINE MEDIA UNDER THE TEMPERATURE EFFECTS

Various approaches to describe phase transitions in crystalline media are considered: Landau phenomenological approach of second-order phase transitions as well as Kolmogorov’s, Avrami’s and Christian’s theories of crystallization. An analysis of the existing approaches indicates that they do not always adequately describe the experimental results. A qualitative model for describing the dependence of a crystalline substance heat capacity on temperature at a constant volume is proposed in this paper. The model describes the change in the number of particles of a new phase of a crystalline substance at a constant volume and is based on Einstein principle of detailed balance. An expression for metal heat capacity adequately corresponded to Dulong-Petit heat capacity is obtained. A model for describing the dependence of heat capacity on temperature in case of phase transitions is proposed.

Enforcing detailed balance in the Borgnakke–Larsen redistribution method with temperature dependent relaxation models

For decades, it has been observed that the commonly used Borgnakke–Larsen method for energy redistribution in Direct Simulation Monte Carlo codes fails to satisfy the principle of detailed balance when coupled to a wide variety of temperature dependent relaxation models, while seemingly satisfying detailed balance when coupled to others. Many attempts have been made to remedy the issue, yet much ambiguity remains, and no consensus appears in the literature regarding the root cause of the intermittent compatibility of the Borgnakke–Larsen method with temperature dependent relaxation models. This paper alleviates that ambiguity by presenting a rigorous theoretical derivation of the Borgnakke–Larsen method's requirement for satisfying detailed balance. Specifically, it is shown that the Borgnakke–Larsen method maintains detailed balance if and only if the probability of internal-energy exchange during a collision depends only on collision invariants (e.g., total energy). The consequences of this result are explored in the context of several published definitions of relaxation temperature, including translational, total, and cell-averaged temperatures. Of particular note, it is shown that cell-averaged temperatures, which have been widely discussed in the literature as a way to ensure equilibrium is reached, also fail in a similar, although less dramatic, fashion when the aforementioned relationship is not enforced. The developed theory can be used when implementing existing or new relaxation models and will ensure that detailed balance is satisfied.